TOKYO/DETROIT, June 11 (Reuters) - Takata Corp’s safety crisis deepened on Wednesday after Toyota Motor Corp recalled almost 2.3 million vehicles globally, many for the second time, and the Japanese air bag maker warned that further fixes may be needed.

Toyota, the world’s largest automaker, called back 1.62 million vehicles outside of Japan that it recalled last year as well as 650,000 more in Japan not previously recalled. The additional vehicles brought to more than 7 million the total number of cars equipped with Takata air bags to be called back worldwide over the last five years.

The 2.3 million cars, many of them sold in the United States, are being recalled to replace faulty air bag inflators.

Also on Wednesday, U.S. safety regulators at the National Highway Traffic Safety Administration opened an investigation into vehicles equipped with Takata air bags.

Takata, the world’s No. 2 manufacturer of auto safety equipment, said other automakers may have to issue recalls because of problems with tracking potential defects related to air bag inflators that date back over a decade.

Toyota expanded its recall because Takata said it had discovered record-keeping errors at a Mexican plant where potentially faulty air bag inflators were made in 2001 and 2002.

While Toyota’s recall covers passenger side air bags, NHTSA investigation documents cited reports of both driver and passenger side air bags not working properly or rupturing. Takata said it was cooperating with NHTSA’s probe but declined to comment further.

Toyota’s expanded recall comes at a time when General Motors Co is under intense scrutiny over why it took more than a decade to discover a defective ignition switch linked to at least 13 deaths.

In 2013, carmakers including Toyota, Honda Motor Co , Nissan Motor Co and BMW recalled about 3.6 million vehicles because of flaws in Takata air bag inflators that could cause them to explode in an accident.

Takata did not disclose how much it expected Wednesday’s Toyota recall to cost, but last year’s recall cost the Tokyo-based auto supplier $300 million. The company’s shares were down more than 4 percent when the Tokyo market closed.

Previously, Takata told U.S. safety regulators it improperly stored chemicals and botched the manufacture of the explosive propellants used to inflate air bags. It also kept inadequate quality-control records, making it impossible to identify vehicles with potentially defective inflators.

The Takata-related recall in 2013 was the largest air bag-related recall in history and came after a series of recalls, accidents and at least two deaths alleged to have been caused by faulty air bags.

Toyota said on Wednesday it was expanding its April 2013 recall involving 2.14 million vehicles manufactured between 2000 and 2004. The serial numbers Takata provided for potentially flawed inflators had been incomplete, Toyota said.

In an unusual step, Toyota said it would also instruct dealers in the United States and other overseas markets to begin replacing suspect Takata inflators in all vehicles covered in a recall announced last year. Previously, the automaker had asked dealers only to replace inflators that were defective.

“We have judged that it is more certain to replace everything,” Toyota spokesman Naoki Sumino said.

More than 766,000 Toyota vehicles were affected in last year’s recall in the United States.

NHTSA said it has opened a probe into an estimated 1,092,000 vehicles made by not only Toyota, but also Honda, Nissan, Mazda and Fiat SpA’s Chrysler Group after receiving six reports of air bags not deploying properly in the humid climates of Florida and Puerto Rico.

OTHERS INVESTIGATE

Honda, Nissan and Mazda said they were investigating whether they needed to recall more vehicles due to problems tracking faulty Takata parts. BMW said it was not aware of any impact on its vehicles. Chrysler said its engineers were analyzing the issue and that the automaker is cooperating with NHTSA’s probe.

In January, Takata began investigating whether there were other vehicles with potentially faulty inflators not covered by the previous recalls after being contacted by Toyota, Takata spokesman Toyohiro Hishikawa said.

Toyota spokesman Ryo Sakai said the automaker had been notified of one case in which a defective front passenger-side air bag inflator caused a seat cover to burn and two cases where the inflator ruptured when the air bag deployed.

Toyota vehicles covered by the recall include Corolla and Camry sedans, and Tundra trucks.

The inflators under investigation were manufactured between September 2001 and September 2002 at Takata’s Mexico plant, the company said. Some of the explosive wafers used in the air bag inflator may have been exposed to excessive moisture or pressed into shape with too little force.

That could cause the inflator to explode when the air bag is deployed, potentially sending pieces of shrapnel into the vehicle, the previous investigation found.

It was not immediately clear how many Takata air bag inflators could have defects. Takata said it will supply the replacement inflators in the Toyota recall.